Source: http://vinepair.com/wine-blog/what-it-re...

The balance of sunshine and rainfall, which together form climates, is critical to fine wines. The unique mixes of these two elements are what make Chianti, Bordeaux, and Sonoma wines exceptional and distinctive.

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Viticulturalists look at a combination of drainage, heat retention, fertility, and minerality when examining a potential vineyard site. The round white stones that cover the ground in the Rhone village of Châteauneuf du Pape, for instance, absorb heat, protecting the vines in cool, windy nights. In addition, the rocky soil allows water to drain deep into the earth, encouraging the vines to develop a strong, downreaching root system, which prevents common diseases and death in the face of drought.